Multi-electrode gaseous-discharge tube circuits



Feb. 26, 1957 D. G. A. THOMAS ErAL 2,783,415

l MULTI-ELECTRODE GASEOUS-DISCHRGE TUBE CIRCUITS Filed Feb. 21, 1952 5 Sheets-Sheet 1 ay RM R AHORA/5y AAA l Feb. 26, 1957 D. G. A. THOMAS ETAL 2,783,415

MULTI-ELECTRODE GASEOUS-DISCHARGE TUBE CIRCUITS Filed Feb. 2l, 1952 5 Sheets-Sheet 2 Feb. 26, 1957 D. G. A. THOMAS ETAL 2,783,415

MULTI-ELECTRODE GASEOUSDISCHARGE TUBE CIRCUITS Filed Feb. 21, 195g 5 sneaks-sheet s y, 53d L...`i

/N VE N TORS Bx mud: R "QW ATTORNEY Feb. 26, 1957 D. G. A. THQMAs ETAL 2,'7'83,415

MULTI-ELECTRODE GASEOUS-DISCHARGE TUBE CIRCUITS Filed Feb. 2l, 1952 5 Sheets-Sheet 4 v v ww O e f m l V V V V 71| V VV V O O 0 IL O OO 6 6 6 1 6 66 w I] l "lll-1*' 11.* l I- |l. l. JI. W l f *Il W n u L L 4 7 O/ 3. Mv. 3 5 /R.v\ 6 /RV fx P f a b c d R ATTORNEY Feb. 26, 1957 D. G. A. THOMAS ETAL MULTI-ELECTRODE GASEOUS-DISCHARGE TUBE CIRCUITS Filed Feb. 2l,- 1952 5 Sheets-Sheet 5 I to-4 8 *"z 50V ,Dz/$50 I 47 60V I lv l r 42 l I 43 to 39 l i 40 o-/wvwg lj. -/8ov A 44 i 4/ s2 I S- l I L 68 200V 40V o l +1 sov /NvEA/rona -sov MW@ @UPA/Ey '/q /VOLD M/7S( QM YE QM. ATTORNEY MULTI-ELECTRODE GASEOUS-DISCHARGE. TUBE CIRCUITS David Gurney Arnold Thomas, Deerhurst-Walton,

Gloucestershire, and Edmund Harry Cookc-Yarborough, Faringdon, Berkshire, England, assignors to National Research Development Corporation, London, England Application February 21, 1952, Serial No. 272,851

3 Claims. (Cl. B15-84.6)

This invention relates to electrical circuit arrangements using multi-cathode gaseous-discharge tubes. Circuits according to the invention have applications in electronic calculating machines.

Multi-cathode gaseous-discharge tubes, sometimes referred to as cold cathode counting tubes or polycathode glow tubes, have been described in the literature including an article Polycathode Glow Tube for Counters, by I. l. Lamb and I. A. Brustman (Electronics, McGraw- Hill Publishing Company, November 1949, pages 92-96) an article The Dekatron-a new gold cathode counting tube, by R. C. Bacon and I. R. Pollard (Electronic Engineering, vol. 22, No. 267, May 1950, pages 173-177) and an article Multicathode gas-tube counters, by G. H. Hough and D. S. Ridler (Electrical Communication, vol. 27. No. 3, September 1950, pages 214-226).

In the co-pending application No. 30,715/ 50 there is disclosed an electrical circuit for operating a first or receiving multi-cathode gaseous discharge tube according to a number stored on a second or sending multicathode gaseous-discharge tube so that the number or its complement on another number may be added to a number, including zero, stored on the rst tube. Such an electrical circuit is referred to as a transfer circuit. A multi-digit number may be stored on a cascade of multi-cathode gaseous discharge tubes: one digit on each tube. Such an arrangement is known as a multi-digit store. The number in one multi-digit store may be transferred to another similar store by associating each tube in the one store (the sending store) with a corresponding tube in the other store (the receiving store) by means of a transfer circuit. Such an arrangement would deal with simple operations, but provision must necessarily be made for the carry-over from one digit to the next most significant digit in the receiving store. For example, in an addition operation using a decimal system, when the sum of digits of the same significance exceeds nine a carry-over must be performed to the next most significant digit.

For performing the arithmetical operation of addition of a multi-digit number in a sending store to a multidigit number in a receiving store a carry circuit is required from each tube in the receiving store to the tube representing the next most significant digit. For the operation of subtraction by the addition of a complement it is further required that a carry circuit is provided between the tube representing the most significant digit and the tube representing the least significant digit as the least significant digit should be complemented on a number one greater than the number on which all other digits are complemented. For example, to subtract 347 from 4000, the 347 is complemented on 9999 to give 9652 from the respective transfer circuits set at the subtract position, the 9652 is added to the 4000 to give (l) 3652 and the most significant figure (viz. l) is carried to the least significant figure (viz. 2) to give 3653. (i. e. 4000 less 347). l

To this end, according to the invention, means are States PatentQ ICC provided for directing, at the completion of each transfer operation of a multi-digit number from a sending lstore to receiving store, a pulse from a pulse generator to each tube in the receiving store through a gate circuit opened by a carry-over condition occuring in a tube of preceding signicance.

In one aspect the invention resides in an electrical circuit comprising rst and second multi-cathode gaseousdischarge tubes arranged so that the position of the discharge therein represents a number, means for applying a pulse train to the rst tube to step the discharge on or beyond the output electrode, means for generating an output pulse when said discharge reaches or passes said output electrode, a switch operated by said output pulse to utilise a carry pulse, generated after the termination of said pulse train, to remove the discharge on said second tube and means for restoring said switch.

Other features of the invention are disclosed in the ensuing description of preferred embodiments of the invention made with reference to the drawings wherein:

Fig. 1 shows diagrammatically the arrrangements of the electrodes of one type of multi-cathode gaseous-discharge tube.

Fig. 2 shows pulse forms for operating a tube of the type shown in Fig. 1.

Fig. 3 shows a diagrammatic form of the tube as used in the circuit diagram of Fig. 4.

Fig. 4 is a simple circuit arrangement for transferring a two digit number in a sending store to a receiving store with carryV facilities between the digits yin the receiving store. (The references in brackets on this ligure refer to the waveforms of Figure 5 existing in the connections vof Fig. 4 as shown.)

Fig. 5 shows waveforms in connections in the circuit of Fig. 4. (The numerals in brackets on this figure refer to the connections of Fig. 4 which carry the respective waveforms of Fig. 5.)

Fig. 6 is a circuit diagram of the gate circuit such as may be used as an alternative to gate circuit 37 of Fig. 4.

Fig. 7 shows the waveforms at points in the circuit of Fig. 6.

Identical reference numbers are used for identical components in the two circuits 37a of Fig. 6 and 37 of Fig. 4.

In Fig. 1, nine main discharge cathodes 1 and an output or zero cathode 2 are equally disposed round a central anode 3, and a common connecting wire 4 joins all the cathodes 1. Between adjacent main cathodes and between the zero cathode and adjacent main cathodes there are first guide electrodes 5 and second guide electrodes 6 and these have common connecting wires 7, 8 respectively. Leads 9, 10, 11, 12 are taken from the electrodes as shown. 2 is taken through a resistance to earth or to a small bias potential and the cathodes 1 are earthed. In a typical case the electrodes 5, 6 rest at 60 volts positive and the anode is connected through a resistance of lMSl to a 350 volt H. T. supply.

On lirst switching on a tube such as shown in Fig. 1 a

discharge is set up between an anode and one of the cathodes 1 or 2. To move the discharge tothe next cathode pulse pairs of the form shown in Fig. 2 are applied to the guide electrodes. Pulse 13, of volts negative swing and 1.5 ms. duration is applied to guidev electrodes 5 thus causing the discharge to move from the cathode on which it initially rested to the adjacent electrode 5. At the end of pulse 13, a pulse 14, similar to pulse 13, is applied to guide electrodes 6 to move the discharge on to the adjacent electrode 6 which has become more negative than any adjacent electrode or cathode. At the end of pulse 14 the Vdischarge moves to thecathode 1 adjacent to the electrode 6, and thus the dis- Patented Feb. 26, 1957` For normal operation the cathode i chrgehastcompleted oneV step'between adjacent cathodes.

overlap, but it is important for any time interval between the end of pulse 13 and the start of pulse 14 to be less thanitheideionisation.timetofltlie tube: Y A

IirFigz. 3 'af-multifcathode tube .isirepresented diagrainf matically.-

mostsignificant digit and the discharge int tube 32 repre-l sentingztheleast significant digit of atwo-digitnumber.y The receiving store consists of `two multiscathode tubes 33,34; tube for the most significant digit andltube=34 for .theA least significant digit. Transfer circuits-35,' 36V ofI the;4 type disclosed in the co-pending applicationV 30,715/50 couple tube 31 with tube133 and tube 32 with tube. 34 respectively. A gate circuit-37 is provided-*between tube 34 and tube 33 and is arranged to'be opened by a carry-over condition occurring at the output electrode 39 of tube 34 which is the tube of Vprecedingsig.- nicance relative: to tubeV 33. Iny a similar manner a gate circuit 38 is provided between tube33 tand'V tube 34 andi'is arranged to be opened by a carryover condition occurring at the output electrode 67 of tube 34,- such as wouldbemet in the arithmetical operation of subtraction as previously described; tube 33 being the tube of pre-4 ceding signiiicance relative to tube 34.

Gate circuits 37 and 38 are similar and the detail ofthese circuits is described with reference to circuit 37.

TheV circuit consists of a cold cathode gaseous dischargeV trigger tube 40, triggeredby the output pulse from the output electrode 39 of tube 34, and adouble triodetube 41 which normally conducts by way ofi anode 42v but is switched to conduct via anode 43 bya pulse generated at the cathode 44 of the tube'40" when it is triggered. The anode 42 has a connection 45 back to a pulse gener.; ator 46` for the transmission ofv a tinish7 signal to-that generator. The anode 43thas ia connection 47 including a rectifier 5t), to the second guide electrode 48 of the tube'33xand a connection 49 including a rectifier 51`to the.l anode'of tube 40. The cathode- 52'of'the doubletriodetube has a connection 531 to the pulse generator 46; A'pulse-.train appliedto cathode 52when the tube 41 is conducting via anode 43 allows the first pulse of-the train to pass via that anode but also depresses the voltage vonV the anode of the trigger tube so that itis extinguished to` restore the conducting path yof tube 41"via anode 42', thus allowing only the iirst pulse of that train (the carry pulse) to pass to the tube 33. The pulse generator-'46l has a connection 54 to the first guide electrodes 55,v 56 of tubes 31 and 32 respectively for a` pulse train of the form shown in Fig. 501) and a connection 57to theV second guide electrodes 58, 59 for apulsetrain of the form shown in Fig. 5(11). A connection 60v feeds a pulse train of the form shown in Fig. 5 (c) to the rst guide electrodes 61, 62 of tubes33 and 34 respectively. Other connections include connections 63and 64 from transfer circuits 35', 36 to the second guide electrodes 48;; 65 of tubes 33 and 34 and connections47a, 45a and53z having functionsin relation to circuit38 similar tothatof connections 47, and 53 in relation to: circuit.37. Connection 66 vcarries pulses to the. transfer circuits 35, 36.

Thel operation of the circuit of Fig. 4 willnow be shownI in conjunction with the waveformnof Figz-S, by

considerationI of the simple mass of addingea number" 561 stored in tubes-landv 32 (the sending store)A toa Electrode 16 is the anode,- electrodeL 17`'is-v the-foutput or zero cathode having an-output terminal-'181 number 39 stored in tubes 33 and 34 (the receiving store).t.A

The pulse generator feeds two trains of ten pulses (Figs. 5(51) and 5(b)) by way of connections 54 and 57 to circulate the discharge in tubes 31 and 32 one complete revolution. This resultsv intive pulses being fed to electrode 48. of tube33 (Fig. 5(d.)) andsiX pulses being fed to electrode 65' 'oftube 3.4(Fig. 5(2)) from the respective transfer circuits set at the add" position. A train of nine pulseszin connection@ (Fig..5(c)) couple with they pulses at electrodes 48and 65 to move the discharge in tube 33 by 'tive steps and the discharge in tube 34 by six steps. That is, the discharge-in tube 33 is moved from its third to its eighth discharge electrode and the discharge inv tubeV 34is moved from its -ninth toitstifth discharge electrode passing its output electrode on the Way to set up an `output pulse to trigger discharge tube 4t). The pulse train in connection 6b is extended as shown by the dottedportion of Fig. 5 (c). Theipulse train normally fedl'to connection 66is extended (Fig. 5 (f)'} and switched to. fccdinstead along connection 53. The firstv pulse of this extended train feed via anode 43 (as tube 4l has been switched by the triggering of tube 4Q), and couples withapulse-in the extendedpulse train in connection 6i? to move the discharge in tube33 by one step, that is on to its ninth discharge electrode. in this manner a number, (the sumof'56 and 139), is-stored in the sending store..

Referring to Fig. 6.and Fig. 4 'of thedrawing the gate circuit 37`may'be provided inlieu oi circuit 37 between tube\34ffand"tube33, anda similar circuit maybe provided, inA lieu `of circuit38; between tube 33 and 34.

As stated. abovethetube.V 41 normally conducts by way offanode 42 but it is'swit'cliedtovconduct via anode 43 by a potential genenatedat'the cathode 44 (Fig. 7c) of thel tubet) when it is triggered by the output pulse frorrrelectrode39 (Fig..7b). Tube 49" continues to conduct (Fig. 7c.) until the anode potential is suppressed by a pulse (Fig. 7j) coincident with the pulses fed to cathode 52 (Fig. 7e) of valve 4i. Thetube 4i is held con ducting bywayof anode 43valthough tube 4 has ceased to conduct by'a pulse train fed'to connection 63 (Fig. 5d) from the;` pulse geenrator 46. This arrangement allows the' passage of one pulse onlyvia anode 43 (Fig. 5g) to second. guide electrode 4S to performl the carry'opera tion;

The Waveformsof Fig, 7 represent the potential in the variousfconnections as follows:

Fig. 7a is the waveform' shown in Fig. 5b and is shown for reference purposes.

Fig; 7b is an output pulse from electrode 39 occurring at the point shown in the waveform of Fig. 7a.

Fig. 7c isfthe, waveform at cathode 44 of tube 40.

Fig. 7d is the waveform applied at connection 68.

F ig. 7e. is the waveform applied at cathode 52 of tube 41.

Fig. 7]c is'the waveform applied to the anode of tube 40.

Fig. '7g is the pulse in connection 47 to perform the carry'operation.

We claim:

1. A computingmachine. comprising at least two multi cathode gaseous/discharge tubes constituting a multi digit sending store', at least two further multi cathode gaseous dischargey tubes constituting a multi digit receiving store, a transfer circuitconnected between each pair of tubes of equal significance in the sending and receiving stores, a pulse generator for supplying trains of pulses to said sending store and to said receiving store under the con trol of said transfer circuit, and a carry circuit between tubes'in the receiving store, said carry circuit comprising agate circuit operated byan output condition in a tube of thereceiving store to pass a carry pulse from said generator to another tube in said receiving; store.

2. Av computing machine as claimed in claim l wherein the gate circuit comprises a trigger cold cathode gaseous discharge tube and grid controlled electronic valve, a

connection from the cathode of the trigger tube to the grid of the valve, a connection for feeding pulses to the cathode of the valve from said generator and a rectier coupling the anodes of the trigger tube and the valve so that the change in anode potential of the Valve when a pulse passes through the valve depresses the anode potential of the trigger tube.

3. A computing machine as claimed in claim 1 wherein the gate circuit comprises a trigger cold cathode gaseous discharge tube and two grid controlled electronic valves having a common cathode connection and arranged so that normally one valve conducts and the other is cut off, a connection from the trigger tube to the grid of the normally non-conducting valve to feed a potential to that grid when the trigger tube fires to switch the conducting path from the normally conducting valve to the other References Cited in the le of this patent UNITED STATES PATENTS 2,310,105 Michel Feb. 2, 1943 2,422,583 Mumma June 17, 1947 2,473,159 Lman June 14, 1949 2,575,517 Hagen Nov. 20, 1951 2,679,978 Kandiah June 1, 1954 2,714,179 Thomas et al. July 26, 1955 

